Ben Franklin famously said, Early to bed, early to rise, makes a man healthy, wealthy and wise. This advice has been echoed through the ages, and many have noted the advantages of early rising and encourage developing it as a regular habit. That’s all well and good, but you can also go to bed early, get up early, and still feel pretty crappy. And how much sleep should you get? Conventional wisdom says eight hours. But again, you can get a full eight hours of sleep and still wake up feeling awful. That’s because in the end it’s not so much about the quantity of sleep. It’s about the quality. When you see people’s productivity slipping, lack of sleep is often the culprit.

Studies have shown that sleep happens in a series of cycles, each one lasting on average around 90 minutes (your own natural sleep cycle length might vary from this by as much as 10 minutes in either direction). Each cycle contains an initial long period of sleep without dreaming, a period of REM (rapid eye movement) sleep during which we do dream, and a final short non-REM bit of sleep. Without any disturbances, you will end one 90-minute cycle and, after a bit of limbo time, slip into another 90-minute cycle. You would then at some point really wake up feeling refreshed as long as you completed each cycle. You might wake up after 4.5 hours, 6 hours, 7.5 hours or 9 hours. You would NOT naturally wake up after 8 hours because it’s not a multiple of 90 minutes! And there’s the rub. The worst thing is to have each of your cycles interrupted. That’s when you’ll feel the worst kind of grogginess.

And the only reason we do all our sleeping at night is because we’re expected to work all day. You might notice that animals and infants sleep whenever they feel the urge. Having more than two periods of such rest in a day is called polyphasic sleeping. All your sleep doesn’t need to occur just in one shot during the nighttime hours. In fact, you can squeeze more hours out of your day, if you want to, by dividing up your sleep cycles during at least two different parts of your day.

When I was an undergraduate student back in late 1980s, I spent a semester studying abroad in Valencia Spain. I never did get adjusted to their sleeping patterns. If I went out to a bar or club on a weekday night at 11 pm I’d be the first one there. Everyone else didn’t start showing up until close to midnight. They’d be there for hours and then go to bed and yet get up for a normal day the next day. How did they do it? In that culture, they utilize the siesta, a mid-afternoon nap. In other words, they were engaging in bi-phasic sleeping patterns. I didn’t like the siesta at the time and didn’t use it because when I did I always woke up feeling groggy and disoriented. That was probably because I wasn’t actually completing a multiple of 90 minutes (1 or 2). Without a properly executed siesta, there was no way I could keep up.

One thing you can do is experiment with how many sleep cycles you need to get and still remain alert and productive over a period of time. Some people find that a grand total of 4.5 hours is enough as long as it’s bi-phasic, meaning it’s divided up between two different parts of the day, say a solid three hours at night and then maybe a 90-minute cycle in the evening after work and supper. You can’t do the 4.5 hours in one stretch and then expect yourself to remain alert for the remaining 19.5 hours of the day!

Everyone wants to get the most from their employees, and the more you know about how sleep affects productivity, the better you’ll be able to help those who need it.

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